Biped ambulatory robot

ABSTRACT

A biped ambulatory robot is provided having a structure in which the electrical storage device is arranged to reduce the load on the joints (particularly the knee joints) of the leg members of the robot and to enable easy maintenance of stability of the robot posture. The electrical storage device  19  which is a power supply for operation of the robot is installed on the electrical storage device unit  16  of the torso  1  of the robot, such that the center of gravity A of the electrical storage device exists on the forward side from the center of gravity B of the robot when in a vertically-erect posture and with the electrical storage device  19  removed. In a state in which the robot stands normally on the floor F with the knee joints  14  of the leg members  2  bent forward slightly, the center of gravity C of the entire robot including the electrical storage device  19  exists substantially directly above the knee joints  14  as seen from one side of the robot.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a biped ambulatory robot.

[0003] 2. Description of the Related Art

[0004] The biped ambulatory robots which the inventors and others havestriven to put into practical use in recent years are, in essence,humanoid robots; in well-known biped ambulatory robots, similarly tohumans, two leg members are provided extending from a hip portion at thelower end of an upper body or torso, and two arm members are providedextending from shoulder portions on the right and left sides of thetorso.

[0005] In this type of robot, the operation power to operate the legmembers, arm members or the like can also be supplied to the robot fromoutside via a cable. However, the operable range of such a robot islimited, and cable handling becomes complicated. Consequently, it ispreferable that the robot itself be equipped with a battery or otherelectrical storage device as a power supply for operation.

[0006] However, when an electrical storage device is provided to therobot as the power supply for operation of the robot, an electricalstorage device of comparatively large capacity is necessary in order tosecure sufficient continuous operating time, so that the electricalstorage device is comparatively large and heavy. In view of theconstruction of a biped ambulatory robot, the above electrical storagedevice is generally mounted on the torso of the robot.

[0007] However, the torso, including the electrical storage device, of abiped ambulatory robot with such an electrical storage device mounted onthe torso is heavy, and when the robot is standing on the floor in asubstantially vertically erect posture, a load tends to act on thejoints of the leg members supporting the torso. In particular, in orderto secure the stability of the posture of a biped ambulatory robot whenstanding on a floor, it is preferable that the knee joints of both legmembers be bent slightly in the forward direction, in this case, if themounted location of the electrical storage equipment on the torso of therobot is inappropriate, then a large load tends to act on the kneejoints of the leg members (a large torque acts on the knee joints fromthe torso of the robot). In this case, the capacity of the actuators(electric motors) for the knee joints must be increased, but the kneejoint actuators tend to be constrained by structure and size parameters,and it is difficult to greatly increase the capacity.

[0008] Also, compared with robots having numerous leg members, by itsnature a biped ambulatory robot tends to easily lose stability ofposture upon receiving an external disturbance or other influence.

[0009] For these reasons, the question of where, and in whatconfiguration, to install the heavy electrical storage device on thetorso of the robot has been an important problem for purposes oflightening the load acting on the joints (particularly the knee joints)of leg members, and for securing stability of the robot posture.

[0010] This invention was devised in light of the above considerations,and has as an object the provision of a biped ambulatory robot having anelectrical storage device placement structure which reduces the load onthe joints (particularly the knee joints) of the robot leg members, andenables the easy securing of stability of the robot posture.

[0011] Another object of this invention is to provide a biped ambulatoryrobot enabling easy attachment to and detachment from the robot of theelectrical storage device.

SUMMARY OF THE INVENTION

[0012] In order to attain these objects, the biped ambulatory robot ofthis invention comprises an electrical storage device as a power supplyfor robot operation and two leg members, and which stands on a floor ona standing posture in which a knee joint in the middle portion of eachof the leg members is bent further in the forward direction from therobot than in a vertically-erect posture in which each of the legmembers is extended in the vertical direction, wherein said electricalstorage device is mounted in an electrical storage device unit providedon the torso of said robot, such that the center of gravity of saidelectrical storage device exists at a position further forward than thecenter of gravity of the robot without said electrical storage device inthe vertically-erect posture, and the center of gravity of the robotwith the electrical storage device thus mounted in the standing postureexists substantially directly above the knee joint of each of the legmembers, as seen from one side of the robot.

[0013] In this specification, the vertically-erect posture of the robotmeans the posture in which the two leg members of the robot are extendedin the vertical direction, and the entire robot is extended in thevertical direction. The above standing posture is the same posture asthe above vertically-erect posture for each of the components of therobot other than the two leg members (torso, arm members, or the like).In this specification, the anteroposterior direction of the robot is thedirection perpendicular to both the direction in which the two legmembers of the robot are aligned while the robot is in thevertically-erect posture (the robot lateral direction), and to thevertical direction.

[0014] In this invention, by ensuring that the center of gravity of theabove electrical storage device, in the state in which the electricalstorage device is mounted in the above electrical storage device unit,exists in a position which is further forward than the center of gravityof the robot in the case where the robot is in the vertically-erectposture and the electrical storage device is removed, when the robot isviewed from one side (when the robot is viewed from a lateral direction)in the above standing posture with the knee joints of the two legmembers of the robot bent somewhat toward the front compared with thevertically-erect posture, the center of gravity of the entire robot,including the above electrical storage device, can be made to exist in aposition which is substantially directly above the knee joints of thetwo leg members of the robot. As a result, in the above standingposture, as the basic posture when the robot is standing normally on afloor, the torque acting on the knee joint of each leg member from theupper side of the robot is comparatively small, and the load acting onthe knee joints can be lightened.

[0015] Further, control is generally exercised to stabilize the postureof biped ambulatory robots based on an inverted-pendulum dynamic modelsuch as that disclosed for example in Japanese Patent Laid-open No.5-337849 or in U.S. Pat. No. 5,459,659. This posture-stabilizationcontrol uses the behavior of an inverted pendulum in apseudo-representation of the behavior characteristics of perturbationsin the upper-body position of the robot, to control the torque about theankles of the robot. In a robot for which such posture stabilizationcontrol is performed, there are cases in which it is preferable, as ameans of securing a stabilized robot standing posture, that, in theabove standing posture, a torque which causes the robot to lean forwardsomewhat acts from the upper-body side about the ankles of both legmembers of the robot. In the case of the biped ambulatory robot of thisinvention, the center of gravity of the entire robot as seen from oneside of the robot is positioned substantially directly above the kneejoints of the leg members, bent in the forward direction, so that such atorque can be made to act about the ankles from the torso. As a result,stability of the standing posture of the robot can be easily secured.

[0016] In this way, by means of the biped ambulatory robot of thisinvention, the load acting on by the knee joints of the robot legmembers when the robot is in a posture of standing on a floor can belightened, and in addition, stability of the robot posture can be easilysecured.

[0017] As described above, this invention is especially preferable forbiped ambulatory robots which perform posture stabilization controlbased on an inverted-pendulum dynamic model.

[0018] In this invention, said electrical storage device is mounted insaid electrical storage device unit such that said electrical storagedevice can be installed and removed via an aperture provided in eitherthe front surface or the rear surface of the torso of said robot.

[0019] As a result, with the robot lying supine, facing upward, or lyingprone, facing downward, the electrical storage device can be removedfrom or mounted in the electrical storage device unit, so thatattachment and removal of the electrical storage device can be performedeasily without the robot tipping or the like.

[0020] Further, in this invention said aperture is provided in the frontsurface of the torso of said robot, and said electrical storage deviceunit is provided in a position enabling installation and removal of saidelectrical storage device via said aperture by operation of arm membersextending from the torso of said robot, further comprising auxiliarypower supply means, other than the electrical storage device, whichsupplies power for the robot operation when installing and removing saidelectrical storage device by operation of the arm members.

[0021] By this means, the above electrical storage device can be removedfrom, or installed in, the electrical storage device unit throughoperation of the arm members of the above robot itself, while the armmembers of the robot are operated through power supplied by the aboveauxiliary power supply means is being operated. Hence attachment anddetachment of the electrical storage device can be easily performed bythe robot itself.

[0022] The above auxiliary power supply means may be, for example, anauxiliary electrical storage device (which need not have such largecapacity), mounted on the robot in addition to the above electricalstorage device. Alternatively, the auxiliary power supply means may be acomponent, provided on the robot exterior, which can be connected byfreely attaching to and detaching from a commercial power supply orother external power supply, and which receives operating power from theexternal power supply (specifically, a component comprising a cable forconnection to the above external power supply, and a rectifying circuit,voltage regulator circuit or the like).

[0023] In this invention, in which an electrical storage device can befreely attached and detached via the above aperture as described above,in a state in which said electrical storage device to said electricalstorage device unit releasably, in the state in which the electricalstorage device is mounted in the electrical storage device unit.

[0024] As a result, through the above clasping means, it is possible toprevent the unintended separation of the above electrical storage devicevia the above aperture due to shock or other force applied to the robotduring robot operation.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]FIG. 1 is a perspective view showing the entire configuration ofone embodiment of the biped ambulatory robot of this invention;

[0026]FIG. 2 is a side view of the robot of FIG. 1; and,

[0027]FIG. 3 is a perspective view showing the configuration of theclasping mechanism of the electrical storage device comprised by therobot of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] An embodiment of the biped ambulatory robot of the presentinvention is explained referring to FIG. 1 through FIG. 3. FIG. 1 is aperspective view showing the entire configuration of the bipedambulatory robot of this embodiment; FIG. 2 is a side view of the robot;and FIG. 3 is a perspective view showing the configuration of theclasping mechanism of the electrical storage device comprised by therobot.

[0029] First, the overall configuration of the biped ambulatory robot ofthis embodiment is explained in summary, referring to FIG. 1. The robotis a humanoid robot, comprising an upper body or torso 1, a pair of legmembers 2, 2, a pair of arm members 3, 3, and a head member 4.

[0030] The torso 1 of this robot comprises a main body 5, from which theleg members 2, 2 and arm members 3, 3 extend, and which supports thehead member 4, and a sub-body 6, provided on the rear surface of themain body 5.

[0031] Shoulder portions 7, 7 are formed on both the left and rightsides of the upper portion of the main body 5, and an arm member 3extends from a shoulder joint mechanism, not shown, incorporated intoeach of these shoulder portions 7. Each arm member 3 has, between thehand portion 8 and shoulder portion 7, in order from the side of theshoulder portion 7, an elbow joint 9 and a wrist joint 10.

[0032] A hip portion (waist portion) 11 is formed at the lower end ofthe main body 5; from a pair of thigh joints 12, 12 provided on theright and left sides of this hip portion 11, the respective leg members2 extend downward. Each of the leg members 2 has, between the footportion 13 and thigh joint 12, in order from the thigh joint 12, a kneejoint 14 and an ankle joint 15.

[0033] Each of the joints of the above leg members 2 and arm members 3is driven by an electric motor, not shown. The above head portion 4 issupported by the upper end of the main body 5, and incorporates an imagepickup device (not shown) for visual perception by the robot.

[0034] The structure of the above torso 1 is here explained, referringto FIG. 2. The main body 5 of the torso 1 incorporates, on the upperside of the above hip portion 11, an abdominal body frame 16 in theportion corresponding to the abdomen of the main body 5, and alsoincorporates, in the upper portion of the main body 5 (the portioncorresponding to the chest), an upper body frame 17, fixed in placeabove the abdominal body frame 16. The main body 5 comprises a pluralityof exterior panel members 18, covering the front and side surfaces ofthese body frames 16, 17, and installed on the body frames 16, 17. Theabdominal body frame 16 is linked to the thigh joints 12 of each legmember 2 via a link mechanism or similar, not shown, incorporated in thehip portion 11 at the lower end of the main body 5.

[0035] Of the exterior panel members 18, the abdominal exterior frontpanel 18 a covering the front surface of the abdominal body frame 16,though not shown in detail, is mounted in a freely attachable anddetachable manner to the abdominal body frame 16 by, for example,installing protruding members provided in the rear face into latchingholes provided in the abdominal body frame 16. The abdominal exteriorfront panel 18 a can then be removed from the abdominal body frame 16 bymoving in the forward direction, as shown by broken lines in FIG. 2.

[0036] A detailed explanation is given below, but an electrical storagedevice 19 is mounted, in attachable and detachable manner, on theabdominal body frame 16 as the main operating power supply for therobot.

[0037] The above sub-body 6 of the torso 1 incorporates a sub-body frame20 fixed on the rear surface of the above abdominal body frame 16 andthe upper body frame 17. On this sub-body frame 20 are mounted a drivercircuit unit 21 for an electric motor (not shown) to drive each of thejoints of the above leg members 2 and arm members 3; a control unit 22(hereafter ECU 22) which handles control of robot operation; a DC/DCconverter 23 which converts the voltage level of the above electricalstorage device 19 into the level required for operation of electricalmotors or the like; and an auxiliary electrical storage device 24 as anauxiliary power supply means to supply power for temporary operation ofthe robot. A cabinet-shape body cover 25, which covers the drivercircuit unit 21, ECU 22, DC/DC converter 23, and auxiliary electricalstorage device 24, is mounted on a bracket 25 a extending from the aboveupper body frame 17. The sub-body 6 is thus configured.

[0038] The above abdominal body frame 16 of the main body 5 functions asan electrical storage device unit in which the above electrical storagedevice 19 is mounted, and is formed in a U-shape as seen from one side.In this abdominal body frame 16, the electrical storage device 19 isaccommodated in the space between an upper horizontal posture frame 16 band a lower horizontal posture frame 16 a (hereafter, this space isreferred to as the interior space of the abdominal body frame 16), theelectrical storage device 19 is supported on the lower horizontalposture frame 16 a in a manner enabling free sliding in theanteroposterior direction. Here the aperture 16 c in the front end ofthe abdominal body frame 16 opens toward the front of the robot when theabove abdominal exterior front panel 18 a is removed, as describedabove. The above electrical storage device 19 is installed, in a mannerenabling installation and removal, into the interior space of theabdominal body frame 16, from the above aperture 16 c toward thevertical posture frame 16 d at the back end of the abdominal body frame16, and thereby mounted in the abdominal body frame 16.

[0039] A receiving connector 26 is provided, protruding toward thefront, on the vertical posture frame 16 d on the back end of theabdominal body frame 16, and is connected to the above DC/DC converter23. A power feed connector 27 (connector to output the voltage of theelectrical storage device 19), which mates with and can be freelyattached to and detached from the receiving connector 26, is provided onthe rear surface of the electrical storage device 19. The power feedconnector 27 mates with the receiving connector 26 when the electricalstorage device 19 is installed into the interior space of the abdominalbody frame 16 as described above.

[0040] Plate members 16 e are mounted on both the left and right sidesurfaces of the abdominal body frame 16; the lateral-direction (widthdirection) position of the electrical storage device is constrained bythese plate members 16 e.

[0041] In this embodiment, the center of gravity of the electricalstorage device 19 in the state in which, as described above, theelectrical storage device 19 is mounted in the abdominal body frame 16,is for example at point A in FIG. 2 (hereafter, point A is called theelectrical storage device center of gravity A). Further, if the two legmembers 2, 2 are extended in the vertical direction as shown by thebroken lines in FIG. 2, and the two arm members 3, 3 are extendeddownward in the vertical direction, and the entire robot is extended inthe vertical direction, in the vertically erect robot posture, then thecenter of gravity of the entire robot in a state in which the electricalstorage device 19 is removed from the abdominal body frame 16 exists at,for example, point B in FIG. 2. Hence the abdominal body frame 16 isprovided such that the electrical storage device 19 is mounted at aposition such that the electrical storage device center of gravity Aexists somewhat further forward than the center of gravity B (hereaftercalled the vertically-erect posture fundamental center of gravity B)when the robot, with electrical storage device 19 excluded, is in thevertically-erect posture. Details are described below, but in thisembodiment, when the robot is made to stand on the floor F with theelectrical storage device 19 mounted in the abdominal body frame 16 asdescribed below, the center of gravity of the entire robot existsbetween the above electrical storage device center of gravity A and thevertically-erect posture fundamental center of gravity B, at the point Cin FIG. 2.

[0042] As explained above, an abdominal body frame 16 equipped with anelectrical storage device 19 is further provided with a claspingmechanism 28 (clasping means) to clasp the electrical storage device 19at the front end of the lower horizontal posture frame 16 a to theabdominal body frame 16.

[0043] This clasping mechanism 28 may be, for example, configured asshown in FIG. 3. That is, the clasping mechanism 28 comprises a rod 30provided so as to traverse, in the lateral direction, the cut-outportion 29 formed in the front end of the lower horizontal posture frame16 a of the abdominal body frame 16. The two ends of the rod 30 areinstalled into the installation holes 31, 31 formed in the lowerhorizontal posture frame 16 a, in a manner enabling free sliding in thelateral direction. Further, the left end of the rod 30 is impelled inthe rightward direction by a spring 32 housed in the left-sideinstallation hole 31. In the portion of the rod 30 exposed in the abovecut-out portion 29 is formed a clasping pin 33, protruding upward.Normally, with the electrical storage device 19 mounted in the abdominalbody frame 16, this clasping pin 33 is moved together with the rod 30 tothe position indicated by the solid lines in FIG. 3 by the impellingforce of the spring 32. At this position, the clasping pin 33 is incontact with the front surface of the electrical storage device 19, andas a result the electrical storage device 19 is clasped such that itcannot be removed from the interior space of the abdominal body frame 16(below, the position of the clasping pin 33 indicated by solid lines inFIG. 3 is called the clasped position).

[0044] On the other hand, in this embodiment a groove 19 a is formed inthe lower surface of the electrical storage device 19, extending in theanteroposterior direction from the front edge to the back edge. Theclasping pin 33 of the above clasping mechanism 28, when moved inopposition to the impelling force of the above spring 32 in the leftwarddirection to the position indicated by the broken lines in FIG. 3,opposes the groove 19 a in such a manner that the upper end of theclasping pin 33 can enter into the groove 19 a in the electrical storagedevice 19 mounted in the abdominal body frame 16. In such a state inwhich the upper end of the clasping pin 33 opposes the groove 19 a inthe electrical storage device 19, by moving the electrical storagedevice 19 in the anteroposterior direction, the electrical storagedevice 19 can be installed into and removed from the interior space ofthe abdominal body frame 16 (hereafter, the position of the clasping pin33 indicated by the broken lines in FIG. 3 is called the unclaspedposition). Further, the clasping mechanism 28 comprises a lock pin 34,mounted to enable rotation about the shaft portion 34 a on the lowerhorizontal posture frame 16 a facing the above cut-out portion 29. When,with the above clasping pin 33 moved into the above unclasped position,this lock pin 34 is rotated 180° about the shaft portion 34 a from thestate shown by the solid lines in FIG. 3, the lock pin 34 makes contactwith the lower portion of the right-hand surface of the clasping pin 33,as shown by the broken lines in FIG. 3. As a result, the clasping pin 33is locked together with the rod 30 in the unclasped position by the lockpin 34, opposing the impelling force of the spring 32.

[0045] In a clasping mechanism 28 configured in this way, by moving theclasping pin 33 to the unclasped position in opposition to the impellingforce of the spring 32 and using the lock pin 34 to lock the claspingpin 33 in the unclasped position, the electrical storage device 19 canbe removed from or installed into the interior space of the abdominalbody frame 16 in the anteroposterior direction. Here, during movement ofthe electrical storage device 19 in the anteroposterior direction, theupper end of the clasping pin 33 moves along the interior of the groove19 a in the electrical storage device 19. When the electrical storagedevice 19 is installed from the above aperture 16 c into the interiorspace of the abdominal body frame 16, and the above power feed connector27 of the electrical storage device 19 is mated with the above receivingconnector 26, the clasping pin 33 withdraws from within the groove 19 aof the electrical storage device 19. In this state, when the lock on theclasping pin 33 by the lock pin 34 is released, the impelling force ofthe spring 32 causes the clasping pin 33 to move from the unclaspedposition to the clasped position. Having moved to the clasped position,the clasping pin 33 makes contact with the front surface of theelectrical storage device 19, and by this means the electrical storagedevice 19 is clasped such that removal from the interior space of theabdominal body frame 16 is not possible.

[0046] Though not shown in FIG. 2, the clasping pin 33 and lock pin 34of the clasping mechanism 28 exist in positions which can be reached bythe hand portion 8 of each arm member 3 of the above robot in a state inwhich the abdominal exterior front panel 18 a is removed.

[0047] Also, though not shown in the figure, the biped ambulatory robotof this embodiment further comprises, in addition to the above-describedconfiguration, sensors to detect the operating positions (the rotationpositions of electric motors driving each joint) of each of the jointsof each leg member 2 and arm member 3, sensors to detect the load andtorque acting on the foot portion 13 of each leg member 2 and on thehand portion 8 of each arm member 3, and sensors to detect the angle ofinclination and the inclination angular velocity of the torso 1.

[0048] The above ECU 22 exercises control of robot operation bycontrolling the electric motors driving each joint of the leg members 2and arm members 3, based on information obtained from the above sensorsand a program specified in advance, or based on instructions andinformation sent by wireless communication from outside. Here the ECU 22exercises control to stabilize the robot posture by controlling theoperation of each of the joints of the leg members 2 based on aninverted-pendulum dynamic model such as that in, for example, JapanesePatent Laid-open No. 5-337849 or U.S. Pat. No. 5,459,659.

[0049] Also, in this embodiment the above electrical storage device 19and the auxiliary electrical storage device 24 may be, for example,lithium-ion batteries or other secondary batteries able to receiveelectricity, or electric double-layer capacitors or other large-capacitycapacitors.

[0050] When the above-described biped ambulatory robot of thisembodiment is made to stand normally on a floor F, the above ECU 22,while exercising control to stabilize the posture, causes the robot tostand on the floor F via the two leg members 2 in the standing postureshown by the solid lines in FIG. 2 (hereafter called the basic standingposture). In this basic standing posture, the posture is, except for theleg members 2, the same as the above vertically-erect posture, with thetorso 1 extended in the vertical direction, and both the arm members 3,3 also extended downward in the vertical direction.

[0051] On the other hand, in the basic standing posture, the knee joints14 of each of the leg members 2 are bent further forward than in thecase of the vertically-erect posture shown by broken lines in FIG. 2; inthis basic standing posture, the robot stands on the floor F. The twoleg members 2 are aligned in the robot lateral direction (in thedirection in which the thigh joints 12, 12 of the two leg members 2, 2are aligned).

[0052] In this case, the center of gravity of the entire robot(including the electrical storage device 19) in the basic standingposture (hereafter called the entire-robot standing-posture center ofgravity) exists at point C in FIG. 2, and this entire-robotstanding-posture center of gravity C is, as shown in the figure,positioned substantially directly above the knee joints 14 of the legmembers 2 in the basic standing posture, as seen from one side of therobot. In other words, in this embodiment, the position of the aboveelectrical storage device center of gravity A is set, relative to theabove vertically-erect posture center of gravity B, such that theentire-robot standing-posture center of gravity C exists directly abovethe knee joints 14 of the leg members 2 when the robot is in the basicstanding posture (as seen from one side of the robot; similarly below).The mounting position of the electrical storage device 19 with respectto the abdominal body frame 16 is set such that, when the electricalstorage device 19 is mounted in the abdominal body frame 16, the actualcenter of gravity of the electrical storage device 19 is positioned atthe electrical storage device center of gravity A.

[0053] The position in the robot lateral direction (the directionperpendicular to the plane of the paper in FIG. 2) of the entire-robotstanding-posture center of gravity C is substantially the centerposition in the lateral direction.

[0054] In this way, because the entire-robot standing-posture center ofgravity C exists substantially directly above the knee joints 14 of theleg members 2, there is no large torque due to the gravity of the sideof the torso 1 of the robot acting on the knee joints 14. As a result,the load acting on the knee joints 14 in the above basic standingposture is small, and the robot can be made to stand on the floor F inthe above basic standing posture without difficulty, even if thecapacity and size of the electric motors (not shown) driving the kneejoints 14 are comparatively small.

[0055] In the above basic standing posture, because the entire-robotstanding-posture center of gravity C is positioned directly above theknee joints 14 of the leg members 2, a torque acts from the side of thetorso 1 on the ankle joints 15 of the leg members 2 in a directioncausing the robot to lean forward slightly. Consequently, control tostabilize the robot posture based on an inverted-pendulum dynamic modelcan be performed satisfactorily, and stability of the robot posture inthe basic standing posture can be maintained smoothly.

[0056] The biped ambulatory robot of this embodiment can itself performoperations to replace the electrical storage device 19 as follows.

[0057] If for example an instruction is sent to the robot from outsideto the effect that the electrical storage device 19 is to be replaced,the robot first moves (walks) to a prescribed replacement station undercontrol of the ECU 22. Next, the ECU 22 switches the channel for supplyof power to the electrical components (electric motors and similar) ofthe various members of the robot from the electrical storage device 19to the above auxiliary electrical storage device 24, by controlling aswitching circuit, not shown. The ECU 22 then operates the arm members3, 3 to remove the above abdominal exterior front panel 18 a using thehand portions 8 of the arm members 3, 3. By this means, the aboveclasping mechanism 28 and similar is exposed to the outside. The ECU 22then controls the arm members 3, 3 to place the removed abdominalexterior front panel 18 a in a prescribed location, and then using thehand portion 8 of one arm member 3, moves the clasping pin 33 of theabove clasping mechanism 28 from the above clasped position to theunclasped position, and uses the hand portion 8 of the other arm member3 to manipulate the above lock pin 34, locking the clasping pin 33 inthe unclasped position.

[0058] Next, the hand portions 8, 8 of the two arm members 3, 3 of therobot are used to grasp both sides of the electrical storage device 19and pull the electrical storage device 19 forward from the interiorspace of the abdominal body frame 16, to remove the electrical storagedevice 19. After placing the removed electrical storage device 19 in aprescribed location, the two hand portions 8, 8 of the robot are used tograsp another new electrical storage device 19. The new electricalstorage device 19, thus grasped, is mounted in the abdominal body frame16 by the procedure opposite that used to remove the electrical storagedevice 19 as described above. After thus mounting the new electricalstorage device 19 in the abdominal body frame 16, the ECU 22 switchesthe channel for supply of power to the electrical components (electricmotors and similar) of the various members of the robot from theauxiliary electrical storage device 24 to the above electrical storagedevice 19 by control of a switching circuit, not shown.

[0059] Hence in this embodiment, by using the power from the auxiliaryelectrical storage device 24, the robot itself can perform the operationto remove and install the electrical storage device 19. In this case,the auxiliary electrical storage device 24 need only have capacitysufficient to provide power to perform the removal and installation ofthe electrical storage device 19, and so can be very small andlightweight compared with the electrical storage device 19.

[0060] In the above, the case in which the robot itself performs removaland installation of the electrical storage device 19 was explained; andin the robot of this embodiment, the aperture 16 c of the abdominal bodyframe 16 in which is mounted the electrical storage device 19 is on thefront side of the robot. Consequently, an operator could easily performby hand operations to remove and install the electrical storage device19 with, for example, the robot in a supine position and facing upwards.In this case, the electrical storage device 19 could be removed from andinstalled with the robot supine and facing upwards, that is, in a statein which there would be no danger of the robot falling or otheraccidents.

[0061] In the embodiment described above, the aperture 16 c of theabdominal body frame 16 in which is mounted the electrical storagedevice 19 is provided in the front surface of the robot, in order thatthe robot itself can perform operations to remove and install theelectrical storage device 19. In cases where an operator performs theremoval and installation of an electrical storage device by hand, anaperture of the electrical storage device unit can also be provided inthe rear surface of the robot; in this case, operations to install orremove an electrical storage device can be performed with the robotlying prone, face downward.

[0062] Also, in the above embodiment an auxiliary electrical storagedevice 24 is mounted on the robot as an auxiliary power supply means tosupply power to operate the robot in order that the robot may itselfperform removal and installation of the electrical storage device 19.However, this auxiliary power supply means may also, for example, supplyoperating power to the robot from a commercial power supply or similaroutside the robot. In such cases, for example, the robot may alsocomprise a freely extractable power cord; after the robot itselfextracts this power cord and connects it to an external power supply,the robot may itself perform operations to remove and install theelectrical storage device, similarly to the above embodiment.

[0063] Also, in the above embodiment, the above clasping mechanism 28was described as such that clasping and unclasping of the electricalstorage device 19 is performed by manual operations; however, the robotmay also comprise clasping means such that clasping and unclasping ofthe electrical storage device is performed by an electric motor or otheractuator mounted in the robot.

What is claimed is:
 1. A biped ambulatory robot, comprising anelectrical storage device as a power supply for robot operation and twoleg members, and which stands on a floor on a standing posture in whicha knee joint in the middle portion of each of the leg members is bentfurther in the forward direction from the robot than in avertically-erect posture in which each of the leg members is extended inthe vertical direction, wherein: said electrical storage device ismounted in an electrical storage device unit provided on the torso ofsaid robot, such that the center of gravity of said electrical storagedevice exists at a position further forward than the center of gravityof the robot without said electrical storage device in thevertically-erect posture, and the center of gravity of the robot withthe electrical storage device thus mounted in the standing postureexists substantially directly above the knee joint of each of the legmembers, as seen from one side of the robot.
 2. The biped ambulatoryrobot according to claim 1, wherein said electrical storage device ismounted in said electrical storage device unit such that said electricalstorage device can be installed and removed via an aperture provided ineither the front surface or the rear surface of the torso of said robot.3. The biped ambulatory robot according to claim 2, wherein saidaperture is provided in the front surface of the torso of said robot,and said electrical storage device unit is provided in a positionenabling installation and removal of said electrical storage device viasaid aperture by operation of arm members extending from the torso ofsaid robot; further comprising auxiliary power supply means, other thanthe electrical storage device, which supplies power for the robotoperation when installing and removing said electrical storage device byoperation of the arm members.
 4. The biped ambulatory robot according toclaim 2 or claim 3, further comprising clasping means to clasp, saidelectrical storage device to said electrical storage device unitreleasably, in the state in which the electrical storage device ismounted in the electrical storage device unit.